Ultrasonic modulation of scattered light in turbid media and a potential novel tomography in biomedicine.
Ultrasonic modulation of scattered laser light was used to image objects buried in tissue-simulating turbid media. The ultrasonic wave focused into the turbid media modulated the laser light passing through the ultrasonic field. The modulated laser light collected by a photomultiplier tube reflected primarily the local mechanical and optical properties in the zone of ultrasonic modulation. A raster scanning over a heterogeneous turbid medium yielded an image of the medium based on the ultrasound-modulated optical signal. The detectability of modulated signal was estimated using diffusion theory. The dependence of the modulated signal on the off-axis distance of the detector from the optic axis and on the amplitude of ultrasound was studied. The mechanisms of ultrasonic modulation of scattered light are discussed. A theory based on the field autocorrelation function is reviewed as well.
Wang
L V
LV
Optical Imaging Laboratory, Biomedical Engineering Program, Texas A&M University, College Station 77843-3120, USA. lwang@tamu.edu
D007834:Lasers; D008027:Light; D009391:Nephelometry and Turbidimetry; D012542:Scattering, Radiation; D014054:Tomography / Q000379:methods*; D014463:Ultrasonography / Q000379:methods*